Run two RefinableString on Sharepoint Online

Hello Wmatsamangwa 

you can build complex queries with kql and operators like AND or OR:

https://learn.microsoft.com/en-us/sharepoint/dev/general-development/keyword-query-language-kql-syntax-reference#kql-operators-for-complex-queries

You write that it works in one case and not in the other?

Can you explain more with detail description or PrintSceens?

Please make sure, that all content are searchable (major version, check-in, permissions...): https://learn.microsoft.com/en-us/sharepoint/make-sure-content-can-be-found

Best, Dave